It's an important part of the bird's ability to maintain its body temperature.
Air is a poor conductor of heat, so the air trapped among the feathers
prevents the loss of heat in cold atmosphere, and prevents overheating
in hot atmosphere. Much like our wearing several layers of clothing.
The answer is
letter C.
<span>
The interdependence
of body systems is essential because all systems work together to maintain
homeostasis. Homeostasis in body systems refers the regulation of internal
conditions keeping it stable and relatively constant. In humans this refers to
its ability to maintain stability in its internal environment while responding
to changes in external conditions. It serves as a sensor that detects changes
in the conditions that need to be regulated to meet the demands of the
condition and give the necessary feedback. Regulation of body temperature and
the balance between acidity and alkalinity are examples of homeostasis in the
human body.</span>
